Upgrade wabt to version 1.0.39

[alexreinking]

This PR updates the wabt to version 1.0.39, ensuring compatibility with Homebrew and vcpkg (both of which have upgraded).

The docker images have been updated to support this change.

[alexreinking]

I entered the mac-x86-worker-2 buildbot to see what's the matter with simd_op_check_arm. CTest is in fact not swallowing any meaningful output (though I think the bus error is happening before any stdout gets flushed). Here's what I see on the bot:

halidenightly@mac-x86-worker-2 halide-build % ./test/correctness/correctness_simd_op_check_arm 
host is:      target(x86-64-osx-avx-avx2-f16c-fma-sse41)
simd_op_check test seed: 1769531600
zsh: bus error  ./test/correctness/correctness_simd_op_check_arm